The study, conducted by the Aarhus University in Denmark, looked at data on 21,276 childless couples that registered for in vitro fertilization (IVF) treatment between 1994 and 2005, noting how many children were born or adopted and how many of the would-be parents passed away before procreating. Over the same time, 96 of the women and 200 of the men died.

Death rates for women who did not have children were four times higher than women who did and twice as high among men.

While careful to caution that association was not causation, Esben Agerbo, the leader of the study, offered a few theories to explain the results. One was a behavioral difference between the two groups. Parents, perhaps more risk averse, were less likely to die in accidents.

“Perhaps [as a childless guy] I am more prone to buy a big motorcycle or a fast car than family-friendly slow van,” Agerbo said.

Other possible explanations for the study's results are that non-parents are more stressed, that people with children have a lot of social support and that people who are child-free live differently—opting to travel more, eat out more or drink more alcohol.